I've been wondering about the circumstances of Mi-ja's first marriage, if the breakup could have been her fault. She is so quick to jump ship if she thinks she will profit from it. I can see how insecure she must feel to have a son to raise alone, but she's so unreliable with regard to both her men. She's left each of them for the other, how can they trust her? Or maybe they just drool at the chance of touching her, etc., and the brain in their skull isn't working.
She thought she had it made when she met the family, then MIL starts changing the rules-of course your son will go to his father.... (HA,ha.Simpson's bully's laugh)
HAHA.. She's a temptress. It's inevitable that she'll leave Sung-moon because she'd do anything for money. She's kept the old guy in reserve just in case things don't work out with Sung-moon. How horrible! I think her husband probably was going through some financial difficulty of some sort and she basically left him so that she could go off and find men she could live off of. She's not even considering the fact that Sung-moon spends more time with her son that he does with his own two children.